    Question

# The heat generated by radioactivity within the earth is conducted outward through the oceans. Assuming the average temperature gradient within the solid earth beneath the ocean to be 0.07∘C−1 and the average thermal conductivity 0.2calm−1s−1C−1, determine the rate of heat transfer per square meter. Radius of the earth = 6400 km. Further, determine the quantity of heat transferred through the earth's surface each day.

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Solution

## The correct option is B From the previous problem Q=4πλ(T1−T2)r1r2(r1−r2)β(temperature gradient)=T1−T2r1−r2∴Q=4πλβr1r2Here r1=r2r(radius of the earth)∴Q=4πλβr2Rate of heat transfer through unit area=4πλβr24πr2=λβ=0.2×0.07=14×10−3 calHeat transfer per day=14×10−3×4π(6.4×106)×86400=6.2×1017 cal  Suggest Corrections  0      Similar questions  Related Videos   Thermal Expansion
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